All 7 Session Management with Redis questions
More in Session Management with Redis
Why is Redis a popular choice for storing web application session data? How do you extend a user's session expiration time each time they make a new request, keeping active users logged in? How would you store more complex session data, such as a user's cart contents alongside their basic login information, using Redis? How do you implement a feature that forcibly logs out a specific user across all of their active sessions and devices? How would you design a session management system that supports both a sliding expiration for active users and an absolute maximum session lifetime regardless of activity? What security considerations are important when storing sensitive session data in Redis, such as authentication tokens?
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Redis › Session Management with Redis

How do you monitor the total number of active sessions currently stored in Redis, and why might this metric be useful?

Intermediate

Answer

You could maintain a counter that increments when a new session is created and decrements when one is removed, or periodically use SCAN with a pattern matching your session key naming convention to count matching keys, giving you visibility into concurrent user activity which can be useful for capacity planning and detecting unusual traffic patterns.
SCAN 0 MATCH session:* COUNT 1000
-- or maintain a dedicated counter for efficiency
INCR active_session_count
Real-world example An operations team monitors the count of active sessions throughout the day, noticing a sudden unexpected spike that turned out to indicate a bot attempting to create many fraudulent accounts in a short period.

Common follow-ups: Which approach, scanning or a dedicated counter, is more efficient for this purpose?;What other insights can active session monitoring provide beyond just detecting suspicious activity?

Redis Monitoring & Observability;Redis CLI & Basic Commands
All 7 Session Management with Redis questions